The classic study dates to 2000, from a team lead by Michael Hammer of University of Arizona. They looked at Y-chromosome haplotypes - this is the genetic material passed from father to son down the generations.
What they revealed was that Arabs and Jews are essentially a single population, and that Palestinians are slap bang in the middle of the different Jewish populations (as shown in this figure).
Another team, lead by Almut Nebel at the Hebrew University, Jerusalem, took a closer look in 2001. They found that Jewish lineages essentially bracket Muslim Kurds, but they were also very closely related to Palestinians. In fact, what their analysis suggested was that Palestinians were identical to Jews, but with a small mix of Arab genes - what you would expect if they were originally from the same stock, but that Palestinians had mixed a little with Arab immigrants.
That's very un-PC.